Wake-up mechanisms are used to start up seldom-used processes in an electronic device. The components used for the process may draw a relatively large amount of power. Therefore, it may be desirable to have the process in an off configuration when not in use. An exemplary process that may be woken-up on an as needed basis is the pairing between two Bluetooth capable devices, such as a mobile telephone and a handsfree headset. During a pairing process, the two units may exchange address and key information that are used to define a trusted environment for future encounters.
Conventionally, pairing over Bluetooth involves a number of actions to be completed by the user. In the case of a phone and headset pairing, the headset needs to be put in a discoverable mode, typically by pushing a button for five or more seconds. Also, the phone needs to be put in an “add a new device” mode using a phone menu.
At least one method has been attempted to simply this procedure without weakening the security aspect of the pairing. In particular, near field communication (NFC) has been used to transfer the address and key information. Alternatively, NFC has been used to wake-up the Bluetooth radios of the headset and phone, and to put the devices into their respective pairing modes.
However, there are drawbacks with this approach. For instance, NFC is based on magnetic coupling and needs a large antenna to operate satisfactory. As a result, NFC antennas are difficult to embed in small, wearable devices, such as headsets. In addition, the NFC operation is not symmetrical in the sense that one device wakes up the other rather than waking-up each other. Also, the NFC interrogator draws a relatively large amount of power and conventionally must be turned on so as not to deplete battery charge. Therefore, there is still an action that the user is required to perform using a button or other input functionality. Alternatively, the NFC interrogator may broadcast periodically. But this involves consumption of power for an infrequently occurring event and, therefore, needlessly places a strain on the battery of a portable device.